Showing papers by "Alan R. Katritzky published in 2001"
226 citations
TL;DR: In this article, the importance of melting points in characterization, in the estimation of other physical properties and toxicity, and in practical applications such as ionic liquids is summarized, as are difficulties in the systematic treatment of melting point in terms of QSPR.
Abstract: The importance of melting points in characterization, in the estimation of other physical properties and toxicity, and in practical applications such as ionic liquids is summarized, as are difficulties in the systematic treatment of melting points in terms of QSPR. Classical correlations of melting points of congeneric and diverse sets are discussed together with group contribution methods, combined approaches, and computer simulations.
180 citations
TL;DR: A regioselective synthesis has been developed for the preparation of unsymmetrical 1,3,5-triaryl-4-alkylpyrazolines and -pyrazoles by treatment of alpha-benzotriazolyl-alpha,beta-unsaturated ketones with monosubstituted hydrazines followed by alkylation at the 4-position of the pyrazoline ring.
Abstract: A regioselective synthesis has been developed for the preparation of unsymmetrical 1,3,5-triaryl-4-alkylpyrazolines and -pyrazoles by treatment of α-benzotriazolyl-α,β-unsaturated ketones with monosubstituted hydrazines followed by alkylation at the 4-position of the pyrazoline ring. Reaction of α-benzotriazolyl-α,β-unsaturated ketones with hydroxylamine gives 3,5-disubstituted isoxazoles regioselectively.
157 citations
TL;DR: A quantitative structure property relationship study of the flash point of a diverse set of 271 compounds provided a general three-parameter QSPR model that solved the boiling point equation using the experimental boiling point as a descriptor.
Abstract: A quantitative structure property relationship study of the flash point of a diverse set of 271 compounds provided a general three-parameter QSPR model (R2 = 0.9020, R2cv = 0.8985, s = 16.1). Use of the experimental boiling point as a descriptor gives a three-descriptor equation with R2 = 0.9529. Use of the boiling point predicted by a four-parameter reported relationship gives a three-parameter flash point equation with a R2 value of 0.9247.
152 citations
TL;DR: The potential utility of data reduction methods for the analysis of matrices assembled from the related properties of large sets of compounds is discussed by reference to results obtained from solvent polarity scales, ongoing work on solubilities and sweetness properties, and proposed general treatments of toxicities and gas chromatographic retention indices.
Abstract: The potential utility of data reduction methods (e.g. principal component analysis) for the analysis of matrices assembled from the related properties of large sets of compounds is discussed by reference to results obtained from solvent polarity scales, ongoing work on solubilities and sweetness properties, and proposed general treatments of toxicities and gas chromatographic retention indices.
107 citations
TL;DR: Quantitative structure-toxicity relationships were developed for the prediction of aqueous toxicities for Poecilia reticulata (guppy) using the CODESSA treatment, which makes it possible to predict unavailable or unknown toxins.
Abstract: Quantitative structure-toxicity relationships were developed for the prediction of aqueous toxicities for Poecilia reticulata (guppy) using the CODESSA treatment. A two-parameter correlation was found for class 1 toxins with R2 = 0.96, and a five-parameter correlation was found for class 2 toxins with R2 = 0.92. A five-parameter correlation for class 3 toxins had R2 = 0.85. The correlations for class 4 toxins were less satisfactory. All the descriptors utilized are calculated solely from the structures of the molecules, which makes it possible to predict unavailable or unknown toxins.
77 citations
74 citations
TL;DR: Products from chiral amines were obtained with stereoselectivities of > or = 94%.
Abstract: 1,5,6,10b-Tetrahydropyrrolo[2,1-a]isoquinolin-3(2H)-ones 17a,b, 17d,e, and 5,12b-dihydroisoindolo[1,2-a]isoquinolin-8(6H)-ones 22a−e were prepared by intramolecular cyclizations of 1-(2-arylethyl)-5-benzotriazolyl-pyrrolidin-2-ones 15a,b, 15d,e, and 3-benzotriazolyl-2-(2-arylethyl)-1-isoindolinones 20a−e, respectively, in the presence of titanium chloride. Products from chiral amines were obtained with stereoselectivities of ≥94%.
64 citations
TL;DR: Enhanced correlations of the lipophilicities with the molecular descriptors are disclosed, wherein the influence of the entropy factor is found to predominate.
Abstract: A quantitative structure property relationship investigation was performed on the lipophilicities of a number of hydantoin derivatives as measured by the RP-HPLC retention times provided by Scholl et al. (Scholl, S.; Koch, A.; Henning, D.; Kempter, G.; Kleinpeter, E. Struct. Chem. 1999, 10, 355−366). The lipophilicities (S) were correlated with the theoretical molecular descriptors of the hydantoins obtained using the CODESSA program from the AM1-optimized geometry and electron wave functions. This study discloses enhanced correlations of the lipophilicities with the molecular descriptors, wherein the influence of the entropy factor is found to predominate.
51 citations
TL;DR: 1-[2-Arylthio(oxy)ethyl]-5-benzotriazolyl-2-pyrrolidinones 6a-e, 12 and 3-ben ZTO-1-isoindolinones 9a-f, 14 are readily available from reactions of benzotrizole, 2-(arylsulfanyl)ethylamines 3, or 2-phenoxyethylamine with 2,5-dimethoxy-2
Abstract: 1-[2-Arylthio(oxy)ethyl]-5-benzotriazolyl-2-pyrrolidinones 6a−e, 12 and 3-benzotriazolyl-2-[2-arylthio(oxy)ethyl]-1-isoindolinones 9a−f, 14 are readily available from reactions of benzotriazole (4), 2-(arylsulfanyl)ethylamines 3, or 2-phenoxyethylamine (11) with 2,5-dimethoxy-2,5-dihydrofuran (5) or 2-formylbenzoic acid (8). Lewis acid mediated cyclizations of 6 and 9 produced novel 1,4-benzothiazepines 7a−e and 10a−f, respectively. Cyclizations of 12 and 14 gave 1,4-benzoxazepines 13 and 15, respectively.
48 citations
TL;DR: A new and operationally simple method has been developed for the regiospecific syntheses of 4-(2-oxoalkyl)pyridines from ketones and pyridine in good yields, using triflic anhydride to activate the p Pyridine ring.
TL;DR: In this article, structural evidence for the existence of avinylogous anomeric effect is presented for a series of 4H-4-benzotriazolyl-2,6-diarylpyrans 1a,b and for their benzo-fused derivatives 2−5 and nitrogen analogue 6.
TL;DR: alpha-(Benzotriazolyl)methyl thioethers 1a-e reacted with styrenes under Lewis acid catalysis to give novel polysubstituted thiochromans (3,4-dihydro-2H-1-benzothiopyrans) 3-14 and 16-20 in generally high yields.
Abstract: α-(Benzotriazolyl)methyl thioethers 1a−e reacted with styrenes under Lewis acid catalysis to give novel polysubstituted thiochromans (3,4-dihydro-2H-1-benzothiopyrans) 3−14 and 16−20 in generally high yields. Most thiochromans were isolated as one diastereomer following recrystallization. The configuration and conformation of the products are predicted on the basis of their NMR data. A stepwise reaction, proceeding via a [4+ + 2] cationic polar cycloaddition mechanism, is proposed.
TL;DR: Two four-parameter quantitative structure-property relations gave good correlations for the solubilities of 87 gases and vapors in methanol and 61 in ethanol.
Abstract: Two four-parameter quantitative structure-property relations, with R2 = 0.95 and R2 = 0.97, respectively, gave good correlations for the solubilities of 87 gases and vapors in methanol and 61 in ethanol. All the descriptors used are derived solely from the structures of the molecules, making it possible to predict solubilities for unavailable or unknown compounds.
TL;DR: An efficient one-pot conversion of cinnamic acids and heterocyclic analogs into the corresponding hydrazides in good to excellent yields under mild conditions involves hydrazinolysis of the intermediate N-acylbenzotriazoles.
Abstract: An efficient one-pot conversion of cinnamic acids and heterocyclic analogs into the corresponding hydrazides in good to excellent yields under mild conditions involves hydrazinolysis of the intermediate N-acylbenzotriazoles.
TL;DR: Carboxylic acids are converted into the corresponding homologated acids or esters, using easily available 1-(trimethylsilylmethyl)benzotriazole as a one-carbon synthon.
Abstract: Carboxylic acids are converted into the corresponding homologated acids or esters, using easily available 1-(trimethylsilylmethyl)benzotriazole (1) as a one-carbon synthon. The effectiveness of the reaction has been investigated on six aryl and seven alkyl carboxylic acids.
TL;DR: Electron-rich 3-functionalized-2-aminothiophenes 6 and 1,3-disubstituted- 2-methylthiopyrroles 10 were synthesized from substituted allyl benzotriazoles 2 and isothiocyanates 3 via condensation and subsequent heterocyclization.
Abstract: Electron-rich 3-functionalized-2-aminothiophenes 6 and 1,3-disubstituted-2-methylthiopyrroles 10 were synthesized from substituted allyl benzotriazoles 2 and isothiocyanates 3 via condensation and subsequent heterocyclization.
TL;DR: Subsequent condensations of these new intermediates afford polysubstituted guanidines, S-aryl isothioureas, and 2-aminoquinazolin-4-thiones.
Abstract: Readily prepared N-functionalized benzotriazole-1-carboximidoyl chlorides are proposed as stable and novel isocyanide dichloride synthetic equivalents. Subsequent condensations of these new intermediates afford polysubstituted guanidines, S-aryl isothioureas, and 2-aminoquinazolin-4-thiones.
TL;DR: Three polymer-supported heterocyclic (triazole 4 and benzotriazoles 2, 8) leaving groups are described and the loading of 8 was clearly superior to those of 2 and 4 and the efficiency was higher than those of previously reported benzotRIazole resins 9a,b in the C-acylation of ketones.
Abstract: Three polymer-supported heterocyclic (triazole 4 and benzotriazoles 2, 8) leaving groups are described. The loading of 8 was clearly superior to those of 2 and 4. The efficiency of 8 was higher than those of previously reported benzotriazole resins 9a,b in the C-acylation of ketones.
TL;DR: The potential utility of data reduction methods (e.g., principal component analysis) for the analysis of matrices assembled from the related properties of large sets of compounds is discussed by reference to results obtained from solvent polarity scales, ongoing work on solubilities and sweetness properties, and proposed general treatments of toxicities and gas chromatographic retention indices as mentioned in this paper.
Abstract: The potential utility of data reduction methods (e.g. principal component analysis) for the analysis of matrices assembled from the related properties of large sets of compounds is discussed by reference to results obtained from solvent polarity scales, ongoing work on solubilities and sweetness properties, and proposed general treatments of toxicities and gas chromatographic retention indices.
TL;DR: Nucleophilic additions to benzoquinone diimines, followed by cyclization with trifluoroacetic acid or 1,3-dicyclohexylcarbodiimide (DCC), provide novel, high-yielding syntheses of 2H-1,4-benzothiazin-3(4H)-ones (3a-f).
Abstract: Nucleophilic additions of α-mercaptoalkanoate esters and β-mercaptoalkanoate acids to benzoquinone diimines, followed by cyclization with trifluoroacetic acid or 1,3-dicyclohexylcarbodiimide (DCC), provide novel, high-yielding syntheses of 2H-1,4-benzothiazin-3(4H)-ones (3a−f) and 2,3-dihydro-1,5-benzothiazepin-4(5H)-ones (5a−c), respectively.
TL;DR: A quantitative structure-reactivity relationship (QSRR) study of the decarboxylation rates of 6-nitrobenzisoxazole-3-carboxylic acid employs the CODESSA program to provide a straightforward interpretation of these solvent effects in terms of molecular parameters.
Abstract: A quantitative structure−reactivity relationship (QSRR) study of the decarboxylation rates of 6-nitrobenzisoxazole-3-carboxylic acid (Kemp, D. S.; Paul, K. G. J. Am. Chem. Soc. 1975, 97, 7305). employing the CODESSA program correlates the effect of 24 solvents with theoretical descriptors to provide a straightforward interpretation of these solvent effects in terms of molecular parameters.
TL;DR: The algistatic activity of 20 substituted 5-aminol-aryl-1H-tetrazoles was correlated with the second order Kier and Hall index, the XY shadow on the XY rectangle and the total hybridization component of the molecular dipole by the CODESSA program in a three parameter equation with r2 = 0.9330.
Abstract: The algistatic activity of 20 substituted 5-amino-1-aryl-1H-tetrazoles was correlated with the second order Kier and Hall index, the XY shadow on the XY rectangle and the total hybridization component of the molecular dipole by the CODESSA program in a three parameter equation with r2 = 0.9330.
TL;DR: In this article, a polysubstituted 5,6-dihydro-4H-1,3-oxazines are synthesized by 1,4-cycloaddition of unactivated olefins with Nacyliminiums from benzotriazole precursors.
Abstract: Novel polysubstituted 5,6-dihydro-4H-1,3-oxazines are synthesized by 1,4-cycloaddition of unactivated olefins with N-acyliminiums from benzotriazole precursors. The configuration and conformation of the products are deduced from NMR investigation. The regio- and exo–endo stereochemistry of the cycloaddition are discussed. Conformations of compounds of six types of substitution (6-mono; 6,6-, 5,6- and 4,6-di; 4,6,6- and 4,5,6-tri) are rationalized on the basis of axial-1,3-repulsion and the anomeric effect.
TL;DR: In this article, a two-parameter correlation was found for class 1 toxins with R2 = 0.96, and a five-parallel correlation was obtained for class 2 toxins with r2 =0.92.
Abstract: Quantitative structure-toxicity relationships were developed for the prediction of aqueous toxicities for Poecilia reticulata (guppy) using the CODESSA treatment. A two-parameter correlation was found for class 1 toxins with R2 = 0.96, and a five-parameter correlation was found for class 2 toxins with R2 = 0.92. A five-parameter correlation for class 3 toxins had R2 = 0.85. The correlations for class 4 toxins were less satisfactory. All the descriptors utilized are calculated solely from the structures of the molecules, which makes it possible to predict unavailable or unknown toxins.